1. Field of the Invention
The present invention generally relates to bitumen emulsions, and more particularly, to special finely divided emulsions of the Phase-Inversion-Temperature (PIT) type containing asphalt and selected emulsifiers, and a method for obtaining said emulsions and the use of special emulsifiers for preparing them.
2. Background Information
Asphalt or bitumen emulsions are well-known materials, which are useful for road-making and for other purposes. Their advantages are ease of handling, because of their lower viscosities than the starting bitumen, and their ability to be applied at lower temperatures in spraying applications and other techniques. There are no environmental problems because in use, the emulsion breaks and the water present evaporates to leave a film of asphalt or bitumen where required. Examples of documents illustrating the state of the art are, e.g., EP 1189990 B1, EP 1179570 A2 or EP 1111010 A1.
There are different methods currently used in the preparation of asphalt or bitumen emulsions using mechanical devices, for example, colloid mills or centrifugal pumps. In conventional methods, the particle size of the final emulsions is typically about 4 to 10 μm. These, procedures, however, are both time and energy consuming, and lead to products which have a limited storage time, since the emulsions thus obtained show a strong tendency to form sediments within a couple of days, especially under temperature stress.